Apparatus for producing a durable press in garments containing cellulose or cellulosic derivatives

ABSTRACT

A novel apparatus for treating fabric articles containing cellulosic material to impart thereto a durable press comprises a treating chamber having means for providing therein formaldehyde and sulphur dioxide gases, and steam according to the weight of the cellulosic material in the fabric articles being treated, and for then cutting off the steam and supplying dry heat to raise the temperature in the chamber to at least 250*F. Further, the chamber has suitable blowers and air ducts to enable the chamber to be flushed with fresh air and/or steam to rid the garments of residual odors.

U ited States' atet Payet et al. 1 Jan. 23, 1973 [54] APPARATUS FORPRUDUCING A 3,166,923 11965 Zacks ..68/5 C DURABLE PRESS IN GARMENTS3,310,363 3 1967 Russell et 31.. 68/5 E X 3,513,669 5/1970 Nirenberg..68/5 C CONTAINING CELLULOSE 0R 3,560,166 2/1971 Walles ..68/5 D xCELLULOSIC DERIVATIVES "mamas? sang; 'IYPEy't,Cincinnati, Ohio; I

John H. Forg, Cincinnati, Ohio McGraw-Edison Coqffilgin,

Filed: Oct. 26, 1971 Appl. No.: 192,285

Related US. Application Data Division of Ser. No. 846,884, Aug; 1, 1969,Pat. No. 3,660,013.

References Cited UNITED STATES PATENTS H [/1957 Sprague et al. ..68/5 DX Primary ExaminerWilliam I. Price Assistant Examiner-Philip R. CoeAttorney-George H. Fritzinger [57] ABSTRACT A novel apparatus fortreating fabric articles containing cellulosic material to impartthereto a durable press comprises a treating chamber having means for.providing therein formaldehyde and sulphur dioxide gases, and steamaccording to the weight of the cellulosic material in the fabricarticles being treated, and for then cutting off the steam and supplyingdry heat Ito raise the temperature in the chamber to at least 250F.Further, the chamber has suitable blowers and air ducts to enable thechamber to be flushed with fresh air and/or steam to rid the garments ofresidual l odors.

10 Claims, 13 Drawing Figures PATENTEDJAN 23 I975 SHEET 2 OF 5 INVENTORSGEORGE L. PAYET JOHN FORG AGENT PATENTEDJAH23 I975 3.712.086

SHEET 4 OF 5 FIG. 8

240 FIG. 9 220 LL t? D O I I- 6-MOISTURE 7T AM) EI- AND T w INJE TION IQ LU PUI6O- 5940 I0) 0.5 I 8 I20 2 2 Ioo V AIR wAs CABINET HEAT N I I PO 2 4 6 BIO I2I4l6l82022 CYCLE TIME-MIN.

260 240 m molsTuRusTEAm) ILL AND 50 Do 2OO INJECTION I- E 5 I :2 Em 46/1 U I60 2 35 I40 IL 5 FIG. IO o I20 2 J 2- I- -A 4 CABINET HEAT ON -TIMEDELAY INVENTORS I GEORGE L. PAYET JOHN H. FORG rw sI;I

BY I 024 6 810 I214 l6 CYCLE TIME MIN. AGENT drapes, etc., as well asthose of non-woven or felted material such as disposables i.e., garmentsmade of paper or paper-like material. The term fabric articles is hereinused to comprehend all the items of this general category.

Cellulose fabrics comprise long polymers having attached (OH) radicalswhich can be reacted with crosslinking molecules between the polymers.These crosslinks permit some slippage between the polymers under stress,but return the polymers to their initial relationships when outsidestresses are removed. By introducing such linkages into a cellulosefabric a durable press is obtained. Formaldehyde is well known toproduce such linkages when diffused through the cellulose fabrics in thepresence of an acidic catalyst, heat and moisture. An example of such acatalyst is sulphurous acid which can be produced in the apparatus fromsulphur dioxide and moisture. It is known on a laboratory scale thatcotton will crosslink in the presence of steam, formaldehyde vapor andsulphur dioxide gas but it is not known that this method can be carriedout dependably and economically on a commercial scale.

An object of the invention is to provide a novel apparatus for carryingout the novel method of our invention in an effective and efficientmanner to produce a durable press having improved properties.

Another object is to provide an apparatus for imparting a durable pressto cellulose fabrics on a commercial scale within a sufficiently shorttime cycle and with lower concentrations offormaldehyde gas and sulphurdioxide gas. v

Anotherobject is to provide an improved apparatus "which is adapted fortreating individual batches of cellulose or cellulosic-blend clothingunder controlled conditions to assure a consistently good durable press.

Another objectis to provide an improved apparatus for imparting, adurable press to cellulosic fabrics, which has a sufficiently lowinstallation cost and short time cycle to render the apparatus practicalfor commercial use by yard goods stores, garment manufacturers, retailstores and cleaning and dyeing shops.

These and other objects and features of the invention will be apparentfrom the following description andthe appended claims.

In the description of our invention reference is had to the accompanyingdrawings, of which:

FIG. 1 is a front vertical section on line l-l of FIG. 3 showing atreating chamber for carrying out the present invention according to oneembodiment thereof;

FIG. 2 is a horizontal section on the line 2-2 of FIG.

FIG. 2a is a fractional sectional view to enlarged scale also onthe line2-2 of FIG. 1;

FIG. 3 is a vertical sectional view on the line 3-3 of FIG. 1;

FIG. 4 is a horizontal sectional view through the blower box on line 4-4of FIG. 1;

FIG. 5 is a fractional sectional view on the line 5-5 of FIG. 4;

FIG. 6 is an exploded diagrammatic view showing an arrangement ofheating channels on the back sides of the internal walls of the treatingchamber;

FIG. 7 is a fractional sectional view on the line 7-7 of FIG. 3 showingthe interconnecting passageways between successive heating channels;

FIG. 8 is a graph showing a typical temperature v. time cycle curve inthe treating process by the embodiment shown in FIGS. 1 to 7;

FIG. 9 is a diagrammatic view showing a front elevation with the frontdoor removed of a treating box according to a second embodiment of theinvention;

FIG. 10 is a graph showing a typical temperature 1 time cycle of thetreating process according to the second embodiment of our invention;

FIG. 11 is a side elevational view of two treating boxes in sequentialarrangement with a conveyor running therethrough; and

FIG. 12 is a top plan view of this sequential box arrangement.

The embodiment of our invention shown in FIGS. 1 to 7 comprises atreating box 10 for receiving batches of prepressed cotton orcotton-blend clothing 1 l and of providing the same with a durable pressby the novel treating method of our invention. This is a rectangular boxwhich may for example be similar in outward size and shape to a largeupright refrigerator. The box is double-walled and insulated between thewalls but has .steam heating channels applied against the outer sides ofthe inner walls for heating the inner treating chamber. The inner wallsare preferable made of aluminum and comprise left and right verticalsidewalls l2 and 13 (FIG. 1), a back wall 14 (FIG. 2), a horizontalbottom wall 15 and a slanting top wall 16 which is inclined downwardlyfrom front-to-back as shown in FIG. 3 to avoid dripping of any possiblecondensation onto the garments being treated. The inner walls are weldedairtight at their seams into a unitary upright construction open at thefront except for a short wall section 17 depending from the top wall 16.(FIG. 3). The remaining front opening is closed by a door-I8 hinged atits left side as indicated at 19. The door ove'rlaps the side edges ofthe inner walls and is sealed airtight thereagainst when closed by anintervening sealing strip 20.

Applied against the outer side of each inner wall of the box and door 18is a series of side-by-side semicylindrical channel members '21. Thesechannel members are welded along their edges to each other and to theinner walls of the box except at their end portions. At the end portionsalternate pairs of adjacent edges of the channel members are cut away at22 from the wall of the box and welded only to each other to provideinterconnecting passageways between the channel members at the endsthereof. (FIGS. 6 and 7). In this way a continuous duct is formedproceeding zigzag along each inner wall of the box with the inner wallconstituting one side of each duct.

Steam for heating the inner chamber is led via a valve V and a pipe 23through the back wail 14 near the top of the box and midway the sidesthereof. The pipe extends to a point near the front door 18 and thencurves upwardly through the top wall 16 to which it is secured airtightby a fitting 24 (FIG. 3). This horizontal portion of the pipe is free ofcondensation because of its heated condition and serves as a rack onwhich hangers for the clothing being treated may be attached. Theextension of the pipe 23 through the top wall is at a junction betweentwo ducts 21 (FIG. 6) so that the steam will divide between the twoducts on the top wall 16 as indicated by the arrows 25. By way ofexample, the steam ducts on the several walls may be connected asfollows: At the end of the last duct at the right side of the top wall16 the steam is led via a nipple 26, connecting tube 27 and nipple 28.to the first duct at the top of the side wall 13; at the end of thelast duct at the bottom of the side wall 13 the steam is led by a nipple29, connecting tube 30 and nipple 31 to the first duct at the top of theback wall 14; and at the end of the last duct at the bottom of the backwall 14 the steam is led back to the source via a nipple 32, tube 33 andintervening trap 34. Similarly, at the end of the last duct at the leftside of the top wall 16 the steam is led via a nipple 35, flexible tube36 and nipple 37 to the top duct on the door 18; at the end of the lastduct at the bottom of the door 18, the steam is lead via a nipple 38,flexible tube 39 and nipple 40 to the first duct at the top of the leftside wall 12; and at the last duct at the bottom of the side wall 12 thesteam is led back to the source via a nipple 41, tube 42 and interveningtrap 43. The bottom wall similarly could be steam heated if desired.

Applied against the outer side of the ducts 21 are layers 44 of asbestospaper, and applied against the asbestos paper are layers 45 about oneand one-half inch thick of fiber glass having its aluminum side facingoutwardly for the purpose of providing a smooth unimpeded surface forair flow. Spaced about one and onehalf inches from the fiber glass arethe respective walls of an outer steel shell 46. This shell has aflanged front edge 47 in a vertical plane which closes the space betweenthe shell and inner walls at the front of the box along the sides andbottom thereof. Also, there is a horizontal flanged edge 48 between thelower portion of the top wall section 17 and the confronting portion ofthe shell. The door 18 underlies the horizontal flanged edge 48 and issealed against the vertical flanged edges 47 at the bottom and sides ofthe door and against a lower strip of the wall 17 below the flanged edge48 at the top of thedoor.

Just beyond the sides, top and bottom of the door 18 there are smallslots or openings 49 in the flanged edge 48, and at the top of the doorthere is a series of openings 50 in the horizontal flanged edge 48.These openings allow air to be drawn inwardly past the side edges of thedoor 18 responsive to an exhaust blower 51 connected by a pipe 52 at theback of the box to the space between the inner walls and shell 46. Thissuction blower draws away gases which may leak from the box past theseal of the door to prevent these gases from escaping into the room inwhich the treating box is located. The chance of any gas leakage is kepthowever at a minimum by a latch 53 diagrammatically indicated in FIG. 2,which holds the door closed with pressure against the seal when thelatch is locked.

Centrally located on the bottom wall 15 of the treating box is aformaldehyde reactor comprising a shallow rectangular case 54 having aninset top wall 55 forming a tray for receiving a quantity of solidparaformaldehyde. This case 54 contains electric heating coils 56connected by an outgoing cable 57 leading through an opening 58 in thebottom wall 15 to a voltage supply. The case 54 is secured by bolts 60to the bottom wall 15. The space between the electric heating coils andthe bottom wall 15 is filled with a fiber glass insulation 61. Thisreactor is adapted to heat the solid paraformaldehyde in the tray 55 andvaporize the same during a treating operation.

Extending through a side wall of the box 10 at a level above the tray 55is a pipe 62 connected to a source 64 of sulphur dioxide (S0 through asolenoid valve 65. Also, in each side wall 12 and 13 at a level abovethe tray 55 is a pipe 66 terminating flush with the inside surface ofthe side wall. These pipes are connected to a source 67 of steam througha solenoid valve 68. A drain pipe 69 and valve 70 leading from thebottom wall of the chamber permits any water condensation to be drainedafter each press cycle.

In the walls of the box near the upper part thereof are portholes 71 and72. These portholes are lined by walls 71a and 72a extending inwardlyfrom the outer shell through the inner side walls of the box. Overlyingthese portholes are respective spiders 73 and 74 secured as by bolts tothe inner walls 12 and 13. Mounted on the central hubs of these spidersare air cylinders 75 and 76 having armatures extending inwardly throughthe portholes and carrying respective dampers 77 and 78 at their innerends. The damper 77 comprises a circular metal plate 77a as of stainlesssteel, a disk 77b as of silicone sponge applied to the metal plate and adisk 77c of solid silicon rubber applied to the sponge disk (FIG. 2a).Similarly, the damper 78 comprises the corresponding parts 78a, 78b and78c. The dampers stand normally open (FIG. 2) and are closed and openedby air pressure to the air cylinders (FIG. 1). In the walls of theportholes are openings 71b and 72b through which air is drawn inwardlyresponsive to the suction blower 51 so that any gas leakage past thedampers 77 and 78 when the dampers are closed may not escape into theatmosphere.

ln the back wall of the box near the bottom thereof is a rectangularopening covered by a damper box 79 (FIGS. 1, 3, 4 and 5) having a rimflange 76 bolted to the outer shell. This damper box has a porthole 80in its back wall near one end thereof coupled by a duct 81 to a suctionblower 82. This blower has an outlet duct coupled by a stack 83 to theoutside. The back'half of the damper box is divided from the front halfby a partition wall 84 having a porthole 85 therein at the other end ofthe damper box. This porthole is closed by a damper 86 (such as thedampers 77 and 78) secured to the armature 87 of an air cylinder 88bolted to the back wall of the box (FIG. 4). Operation of the aircylinders 75, 76 and 88 in an inward direction open these dampers(FIG. 1) to enable the blower 82 to draw the gases from the treatingchamber and to circulate air therethrough. To permit any rising pressurein the treating box to be relieved when the pressure reaches apredetermined level, as when steam and sulphur dioxide are injected intothe box, a blow-off valve 89 is provided in the damper box '79. Thisvalve comprises a tube 90 extending through the partition wall 84 and 7having a turned-up end portion at the outer side of the wall 84 closedby a weighted cap 91 resting on the end of the tube. The cap has aninternal silicone rubber gasket 92 to provide a good seal so long as thepressure is below the blow-off level.

The present method is carried out by placing the garments in the closedchamber and then injecting formaldehyde and sulphur dioxide gases andsteam. During the injection of thesegases the chamber is not heatedother than by the heat of the steam. The initial temperature of thechamber may be at room temperature, say 70 to 80F, or the chamber may bepreheated but not in excess of 150F. The steam is then cut off and thechamber allowed to cool to saturate the treating atmosphere and cause agreater condensation of steam through the fabrics being treated. Whenthe box is initially at room temperature the steam is injected until theinternal temperature reaches approximately 120F, whereupon the steam iscut off and the chamber allowed to cool typically from 10 to 25F. lf thechamber is in a preheated condition i.e., above room temperature not inexcess of 150F the temperature may be allowed to cool after the steam iscut off by more than the temperature rise due to the steam before theauxiliary heating is applied. By proper timing of the auxiliary heating,depending upon the type of auxiliary heating apparatus, the internaltemperature is raised following the temperature drop just noted to atemperature of 250F to complete the crosslinking operation. Thereupon,the chamber is allowed to cool and outside air is circulated through thechamber for several minutes to rid the garments of residual odors. Also,if necessary, steam may thereafter be circulated through the chamber forseveral minutes and then again outside air for several minutes to ridthe garments wholly of any residual odors.

In a more precise procedure for carrying out the above method by thetreating apparatus abovedescribed, consistently good results areobtained starting with the treating chamber at or about room temperatureand with the reactor heater for the paraformaldehyde in a preheatedcondition but not to full vaporizing temperature. The garments to betreated are then placed on coat hangers attached to the pipe 23,

the desired quantity of paraformaldehyde is placed on the tray 55, thereactor heater is turned up to full temperature, and the door 18 and alldampers are closed. Low pressure steam of approximately 4 psi. is thenadmitted via the pipe 66 and sulphur dioxide gas is admitted via thepipe 62 for a period of approximately two minutes during which time theparaformaldehyde is being vaporized. During this period the steam,sulphur dioxide and formaldehyde gases permeate through the fabrics andthe temperature in the chamber rises because of the steam typically toabout l20F. This is shown by the first portion A, of the curve of FIG.8. The time for carrying out this operation is typically about twominutes. At the end of this period the steam valve V is opened to startheating the chamber. However, since the steam ducts 21 are outside thechamber walls, there is a delay in heat transmission into the chambercausing the internal temperature to fall about 25 in the next twominutes as shown by the second portion A of the curve of FIG. 8 beforethe temperature begins to rise from the auxiliary heating. Thistemperature drop is a very important step in the present inventionbecause it causes the treating atmosphere to become saturated with aresultant greater condensation of steam through the fabrics beingtreated. This greater condensation reduces the required concentrationsof formaldehyde and sulphur dioxide and shortens the treating cycle. Atthe end of the two minute temperature drop the heat from the steam ducts25 causes the internal temperature to being to rise. This rise continuesfor a period of about ten minutes as shown by the portion A of the curveof FIG. 8 before the temperature reaches 250F to complete the crosslinkage operation. The time required to bring the temperature to 250F isimportant only from an economy standpoint since the completion of thelinkage reaction depends only on the temperature reaching the 250Fvalue. Accordingly, a time is selected taking into account the usualsteam sources, thermal mass of the box, etc., which enables the boxtemperatures to be increased to 250F or thereabout in a periodcomensurate with practical requirements and with maximum economy. Whenthe temperature reaches 250F the steam valve V is turned off preferablyby automatic control from the thermostat T in'the chamber and thegarments are purged by air and optionally also by steam to remove theresidual odors.

The amounts of formaldehyde and sulphur dioxide for each treatingoperation depend by the present invention on the volume of the treatingchamber. For example, the volume of the treating chamber may beapproximately 35 cubic feet. In terms of percentage by volume atatmospheric pressure the sulphur dioxide range is typically from 0.1 to2 percent, and the formaldehyde range is from 2 to 10 percent. Thisvolume range of formaldehyde is obtained by placing paraformaldehyde onthe tray 55 in an amount from 26.25 grams (2 percent) to 131.1 grams (10percent). However, for maximum results, the sulphur dioxide is providedat a volume percentage of 1.02 percent and the formaldehyde at 6.19percent. This volume percentage of formaldehyde is obtained by placinggrams of paraformaldehyde on the tray 55. The maximum points in theseranges should not be exceeded because more than 2 percent sulphurdioxide will cause undue degradation of the fabric, and concentrationsof formaldehyde above the range noted provides an explosive hazard.

The amount of moisture required for each treating operation is dependentprimarily on the weight of the cellulose in each batch of garments beingtreated. lf the clothing being treated is all cellulose the total weightof the batch is considered in determining the amount of moisturerequired. However, if the clothing is a blend of a given percentage ofcellulose with another fiber, then only that percentage of the overallweight is considered in determining the amount of moisture required. Itis desired that the moisture content of the clothing should reach from10 to 20 percent on a weight basis during a treating operation, butpreferably the moisture content is to be held between 15 to l7 percent.A variable injection of steam into the treating chamber is achieved bycontrolling the time interval the steam valve 68 is held open duringeach treating operation. For this reason the solenoid valve 68 iscontrolled by a timer 94. This timer has a time setting knob 95registering with a scale 96, and has a start button 97 for starting atreating operation and a start button 102 for starting a purgeoperation, as later described. The timer is connected to a power supplyvia a connector cable 98 and is connected to the solenoid valve 68 by aconnector cable 99. Upon placing a batch of clothing in the treatingchamber and then closing the door 18 the operator will press the startbutton 97 to start the flow of steam into the treating chamber for aninterval depending upon the setting of the knob 95. The scale 96 may becalibrated in terms of the weight of cotton cloth in the batch beingtreated so that the operator after weighing a batch can readily set theknob for the right steam injection.

The timer 94 is also connected by a cable 100 to the sulphur dioxidecontrol valve 65 to energize this valve for an interval independent ofthe setting of the knob 95 each time the start button 97 is pressed.However, this time interval of energization of the valve 65 may beadjusted to the desired setting for any given size of treating chamberby an adjusting screw 101 preferably as by a tool such as a wrench orscrew driver.

The purging of the garments to rid them of residual odors is carried outby first replacing the gases in the treating chamber with room air as byopening the dampers 77 and 78 at the sides of the treating chamber,opening the damper 86 of the damper box 79 and starting the exhaustblower 82. After the exhaust blower 82 has run from 3 to minutes toreplace the gases in the treating chamber with outside room air, thegarments may be removed. However, if further purging is required thedampers are closed to seal the treating chamber and the steam purgebutton 102 on the timer 94 is pressed to open the steam valve 68 withouthowever opening the valve 65 controlling the sulphur dioxide gas. Thetimer 94 is adapted to hold the steam valve 68 open for a period of from2 to 5 minutes when the purge button 102 is pressed. After the treatingchamber is again exhausted from two to five minutes as abovedeseribed,the batch of clothing may be removed. Still further, the cycle of addingsteam and of then exhausting the treating chamber may be repeated.

Durability of crosslinks to acidic washing is superior to that found inconventional resinous type durable press. This is shown in Table I bythe crease recovery for acid souring vapor phase treated samples andconventional resinated samples of the same type where the Symbol (W+F)means the recovery along the warp plus the recovery along the fill, itbeing understood that complete recovery in each direction would be 180.

TABLE I CREASE RECOVERY AFTER ACID SOURING WITH SULPHURIC ACIDConventional Durable Press Vapor Phase (W+F) (W+F) Original 304.0 315.0Soaring min. pH 5.0 280.3 306.0 at I75F Soaring 30 min. pH 3.0 276.7305.7 at I75F Softness of hand is much greater than in conventionalresin type durable press as there is no surface resin to give the fabrica harsh" handle.

Retention of hand on successive washing As there is no surface resinwhich is subsequently washed off, vapor phase treated fabrics retaintheir handle after numerous washings, whereas conventional resin typedurable press becomes softer and softer after nominal washings.

Superior Abrasion Resistance of vapor phase samples is due primarily tothe softer hand, as the fabrics have not been embrittled with resins asin the case of resin type durable press. As an example, two like fabricswere compared, one containing conventional resin type durable press, theother the vapor phase treatment. These samples are shown in Table II.

TABLE II ABRASION LOSS OF FIBER WEIGHT IN ACCELERATOR AT 3,000 RPM FOR 3MINUTES Orig. Final Fiber Fiber Sample No. Weight(g) Weight( g) RetainedLost 6l9P Conventional 3.8791 3.1699 l -3 Durable Press 6l 8? VaporPhase 3.9893 3.4217 85.8 l4.2

Durable Press Both good wet and dry wrinkle recovery is evidenced invapor phase durable press fabrics as shown in the following Table III.

TABLE III WET AND DRY CREASE RECOVERY dry crease recovery wet creaserecovery Sample No. W. F. (W+F) W. F. (W+F) 6l8P (Vapor Phase) l55.0l60.0 3l5.0 l52.0 l56.3 308.3 6I9P (Durable Press) I50.0 I543 304.3I32.3 I410 275.3

Stain release is superior in vapor phase treated samples with respect tooily materials. Literature has shown that oily materials adhere to theresinous type crosslinking which are not present in vapor phasecrosslinked samples. A 65/35 polyester cotton blend fabric, one piecedurable press treated with resins in the textile mill was compared tothe same fabric vapor phase treated. These samples were stained andwashed, and are compared in the following Table IV.

TABLE IV STAIN REMOVAL ON RESIN DURABLE PRESS VS VAPOR PHASE DURABLEPRESS No. Chocolate Salad Sample No. Treatment Washes Catsup SyrupDressing 374 Vapor Phase 3 4 4 5 376 Vapor Phase 3 4 4 4+ 37 7 VaporPhase 3 4 4 5 3 79 Resin- Durable Press 3 4+ 4 4- 380 Resin DurablePress 3 4 4 4- Ratings for soil removal are as follows: l No change 2Slight change 3 One half stain 4 Stain not quite gone 5 Stain completelyremoved Alteration capabilities are very simplified where vapor phasetreatments are employed, as garments may be altered prior to renderingthe fabric durable press. In conventional resin type durable press, thealterations must be made after the garment is rendered durable press.Creases are then durable and cannot be changed as alterations require.

In the alternative embodiment of the invention shown in FIGS. 9 and 10,the same form of temperature time relationship during the treatingprocess is obtained to effect the same durable press with the use oflesser concentrations of treating agents than has been heretoforeobtainable and again the period of each treating operation issubstantially reduced. In this embodiment, the steam ducts 21 andinsulation 45 are removed from between the internal chamber walls 12 14and 16 and the outer shell 46, and instead the inside walls 12 14 and 16are covered with a one inch thick insulation 108 of expanded silicaknown as Careytemp, and a series of finned steam-operated heater units109 are mounted on the inside walls against the insulation 108. Theseinternal heating units 109 may comprise three vertically spaced units onthe back wall 14 and three intervening units on each side wall 12 and13. No heating units are placed against the top and bottom walls 15 and16 or against the door 18.

Since the heating units 109 are inside the chamber to heat the internalatmosphere directly they are capable of heating the treating chamberwith relatively little time delay. Accordingly, in carrying out thetreating process starting with the chamber at room temperature, theformaldehyde and sulphur dioxide gases and the steam are provided in thechamber for about 2 minutes causing the internal temperature to riseagain to about l20F from the heat of the steam, as shown by the portionA, of the curve of FIG. 10. Next, the steam injection is cut off and thechamber is allowed to cool for about two minutes without any auxiliaryheating applied. This causes the temperature to fall as shown by theportion A of the curve of FIG. 10. This fall may typically be from l0 to15. The steam is then turned on the heating units 109 causing theinternal temperature to begin to rise immediately as shown by theportion A of the curve of FIG. 10. Further, since the heating units 109are directly in the chamber the internal temperature rises to about 250Fto complete the crosslinkage reaction in only about 6 minutes.Thereupon, as before, this steam is cut off from the heating units 109and the chamber is allowed to cool. Also, the fabrics may then be purgedwith room air and/or steam to rid them of residual odors as may berequired.

In order to expedite the treating of fabric articles by the presentmethod on a production basis two treating boxes 10 may be placed insequential arrangement as shown in FIGS. 11 and 12. The back walls ofthese boxes are removed, and the boxes are set back-to-back with a pairof sliding doors 103 therebetween and with the front doors 18 at thefront and back of the sequential arrangement. The exhausts 51-52 and79-83, and the steam inlet pipes 23, which were on the back walls,

are now appropriately mounted on the right and left walls as indicated.The horizontal portion of the pipe 23 which served as a rack for holdingthe work being treated is now offset suitably and'in its place at alevel just above the doors 18 is a conveyor belt or chain 104. Thisconveyor chain is trained around guide rollers in a complete circuit.The rectilinear portion 104A of the conveyor chain ahead of the firstbox comprises a loading station on which a series of hangers 106 areattached bearing garments or other fabric articles to be treated, andthe rectilinear portion 104B following the second box comprises anunloading station where the hangers are removed. The first box may beused for treating the garments with the steam, formaldehyde and sulphurdioxide, the same as described, and the second box may be used forpurging the garments with room air and/or steam to rid the garments ofresidual odors also in the manner as described. Upon opening the doors18 and 103 the conveyor chain may be advanced as by a motor 107 throughsteps to shift the work loads from the loading station to the first box,and concurrently from one box to the next and from the second box to theunloading station.

The embodiments of our invention herein particularly shown and describedare intended to be illustrative and not necessarily limitative of ourinvention since the same are subject to changes and modificationswithout departure from the scope of our invention, which we endeavor toexpress according to the following claims.

. We claim:

1. An apparatus for treating fabric articles containing cellulosicmaterial to impart a durable press thereto, comprising a treatingchamber for said articles, means for exposing the articles in saidchamber to steam, formaldehyde gas and sulphur dioxide gas, means forheating said chamber after the steam is cut off to a temperature of atleast 250F, a surrounding wall spaced from the wail of said chamber, andmeans for circulating air through the interwall space between saidchamber and said surrounding wall.

2. The apparatus set forth in claim 1 wherein said heating means isprovided in said interwall space in thermal contact with the wall ofsaid chamber.

3. The apparatus set forth in claim 2 including insulating means appliedagainst said heating means and spaced from said outer wall leaving anair space for flow of air from said circulating means.

4. The apparatus set forth in claim 1 wherein said heating means is indirect contact with the treating atmosphere.

5. The apparatus set forth in claim 1 including an air inlet duct forsaid chamber and a damper for said duct, said outer wall having airholes for permitting a flow of outside air into said interwall space inthe vicinity of said air inlet duct, and a suction fan connected to saidinterwall space for causing any leakage of gas through said duct whensaid damper is closed to be drawn via said air holes into said interwallspace and exhausted.

6. The apparatus set forth in claim 1 including a door for said chamberthrough which the chamber is loaded and/or unloaded, said outer wallextending to the boundary of said door and being sealed thereat to thewall of said chamber, said outer wall having air holes at said boundary,and a suction fan connected to said interwall space for drawing airinwardly through said air holes to.

exhaust any leakage of gas from around said door.

7. The apparatus set forth in claim 1 wherein the means for exposing thearticles in said chamber to steam includes means for injecting saidsteam into said chamber, and manually settable means for controlling theamount of steam injected in proportion to the weight of the cellulosicmaterial in the fabric articles being treated.

8. An apparatus for treating fabric articles containing cellulosicmaterial to impart a durable press thereto, comprising a treatingchamber for said articles, means for exposing the articles in saidchamber to steam, formaldehyde gas and sulphur dioxide gas, means forheating said chamber after the steam is cut off to a temperature of atleast 250F, and a top wall for said chamber slanting downwardly to causecondensation thereon to drain downwardly and not drip on the fabricarticles being treated.

9. An apparatus for treating fabric articles containing cellulosicmaterial to impart a durable press thereto, comprising a treatingchamber for said articles, means for exposing the articles in saidchamber to steam, formaldehyde gas and sulphur dioxide gas, means forheating said chamber after the steam is cut off to a temperature of atleast 250F, a rail in said chamber in which hangers bearing said fabricarticles can be attached, and means for heating said rail so that steamis prevented from condensing thereon and dripping onto the fabricarticles being treated.

10. The apparatus set forth in claim 9 wherein the means for heatingsaid chamber includes steam jacketed heating means and wherein said railconstitutes a pipe extending across said chamber for leading steam tosaid heating means.

2. The apparatus set forth in claim 1 wherein said heating means isprovided in said interwall space in thermal contact with the wall ofsaid chamber.
 3. The apparatus set forth in claim 2 including insulatingmeans applied against said heating means and spaced from said outer wallleaving an air space for flow of air from said circulating means.
 4. Theapparatus set forth in claim 1 wherein said heating means is in directcontact with the treating atmosphere.
 5. The apparatus set forth inclaim 1 including an air inlet duct for said chamber and a damper forsaid duct, said outer wall having air holes for permitting a flow ofoutside air into said interwall space in the vicinity of said air inletduct, and a suction fan connected to said interwall space for causingany leakage of gas through said duct when said damper is closed to bedrawn via said air holes into said interwall space and exhausted.
 6. Theapparatus set forth in claim 1 including a door for said chamber throughwhich the chamber is loaded and/or unloaded, said outer wall extendingto the boundary of said door and being sealed thereat to the wall ofsaid chamber, said outer wall having air holes at said boundary, and asuction fan connected to said interwall space for drawing air inwardlythrough said air holes to exhaust any leakage of gas from around saiddoor.
 7. The apparatus set forth in claim 1 wherein the means forexposing the articles in said chamber to steam includes means forinjecting said steam into said chamber, and manually settable means forcontrolling the amount of steam injected in proportion to the weight ofthe cellulosic material in the fabric articles being treated.
 8. Anapparatus for treating fabric articles containing cellulosic material toimpart a durable press thereto, comprising a treating chamber for saidarticles, means for exposing the articles in said chamber to steam,formaldehyde gas and sulphur dioxide gas, means for heating said chamberafter the steam is cut off to a temperature of at least 250*F, and a topwall for said chamber slanting downwardly to cause condensation thereonto drain downwardly and not drip on the fabric articles being treated.9. An apparatus for treating fabric articles containing cellulosicmaterial to impart A durable press thereto, comprising a treatingchamber for said articles, means for exposing the articles in saidchamber to steam, formaldehyde gas and sulphur dioxide gas, means forheating said chamber after the steam is cut off to a temperature of atleast 250*F, a rail in said chamber in which hangers bearing said fabricarticles can be attached, and means for heating said rail so that steamis prevented from condensing thereon and dripping onto the fabricarticles being treated.
 10. The apparatus set forth in claim 9 whereinthe means for heating said chamber includes steam jacketed heating meansand wherein said rail constitutes a pipe extending across said chamberfor leading steam to said heating means.